ABSTRACT
This chapter considers the Mohr’s circle of stress for a fluid with no relative motion between fluid particles. Many devices exploit the hydrostatic pressure distribution. The hydraulic brakes in an automobile take advantage of the fact that pushing on a column of fluid with a certain force transmits the pressure by moving brake fluid through the car’s brake lines. A hydraulic lift in a mechanic’s shop allows a small force to be applied to a small piston area, then transmitted as fluid pressure to a larger area in order to lift a heavy vehicle. Pressure is often measured using liquid columns in vertical or inclined tubes, or manometers. The three most common types of manometers are U-tube and inclined-tube manometers, and piezometers. Fluid pressure causes the diaphragm to deflect, and its deflection is measured and converted into an electrical voltage. An object that is submersed in fluid is subjected to hydrostatic pressure over its entire surface area.
